Noting that the LS2 will have a compression of 10.9, I would like to know the formula relating HP to compression. How much HP would be gained from raising compression in a stock LS6 engine from 10.5 to 10.9?

It appears that milling .015 off the heads will decrease chamber area by 2cc and increase compression to around 10.9 while not having to change any valve train components.

 

You will have to change pushrods if you mill the heads, the ls1,6 rocker arms are non-adjustable.

 

i think LS6 is already 10.8 or so

 

General rule of thumb, for every point gain over 10 to1, you will gain 5% to 7% of the CID of the engine. Example: 10 to 1 to 11 to 1 on a 346 would be 17 to 22 HP.

Chris